As next-generation mobile communication systems emerge, small wireless base stations (hereinafter, “Home eNB”) which are installed in homes and offices and are used by specified subscribers are examined as a part of specifications of LTE (Long Term Evolution), which is discussed in 3GPP (3rd Generation Partnership Project).
Conventional wireless base stations are installed in roofs of buildings to which mobile communication providers subscribe, and the mobile communication providers prepare power sources for the wireless base stations, and connect lines from the wireless base stations to the mobile communication providers' networks. Cells which are provided by the wireless base stations can be generally used by all subscribers who subscribe to the mobile communication providers.
Subscribers of the mobile communication providers may install Home eNB in homes and further prepare power sources and networks. Contrary to the cells from the conventional wireless base stations, the cells provided by the Home eNB can only be used by the subscribers and others who are allowed by the subscribers, such as family members.
The mobile communication providers can more easily expand coverage of mobile communication services by using the Home eNB in comparison to the conventional wireless base stations. Furthermore, communications via the Home eNB allows the mobile communication providers to reduce the costs of the communication charged to the subscribers to a price point that is roughly equivalent to the costs of communication via general fixed networks, thereby encouraging the substitution of fixed networks with mobile telephones networks. As a result, the mobile communication providers can provide new services such as the seamless provisioning of communication services with one home mobile station, in addition to the mobile station outside the home.
FIG. 1 illustrates one example of a cell configuration using the Home eNB. In the drawing, a wireless base station (hereinafter referred to as an “evolved Node B” or an “eNB”) 1 is connected to a mobile communication provider network (mobile communication network) 2, and the wireless base station 1 forms macrocells 3 and 4 at its subordinate positions.
A Home eNB 5 is a compact wireless base station which is provided into the macrocell 4. The Home eNB 5 is connected to the mobile communication network 2 via a public IP (Internet Protocol) network 7, for example, and forms a home eNB cell 8 at its subordinate position.
The Home eNB 5 is connected to the public IP network 7 by a broadband line such as an optical cable or ADSL.
A technique which enables only a mobile station which is allowed to use a base station for communications is known. A technique which performs posting/setting from an ultra-compact base station to a portable network and uses a spread code/identification code which is different from codes of neighborhood base stations in order to avoid interference, and a technique which recognizes intrusion/pulling-out of an in-plant network by positional registration of a mobile station and starts/ends the service are known (for example, see Japanese Laid-Open Patent Publication Nos. 2005-109570 and 2006-261722, 2004-274767).
Various operational forms of the Home eNB are present, one of them being a form of use in which, when the Home eNB is installed in a residential home, only family mobile stations are permitted to access the Home eNB. In such a Home eNB, where subscribers who can use it are limited, there may be cases where no subscriber is present in this coverage area for a long time.
In general, a wireless base station continuously transmits broadcast information even when a subscriber is not present in a coverage area of the base station. When a subscriber moves into the coverage area, the wireless base station instantly accepts a new call request or handover request and continues to provide a smooth and seamless connection to a mobile network.
A similar mechanism is applied to the Home eNB, but because no subscriber may be present in the Home eNB coverage area for a long time, the Home eNB may continue to transmit useless information for a time period in which no subscribers are in the coverage area. This is not efficient because electric power is needlessly consumed and peripheral cells may be unnecessarily interfered with.
Once the Home eNB stops transmitting broadcast information, the Home eNB may not detect the approach of a subscriber who can otherwise use the Home eNB. In this scenario, the Home eNB may not detect the approach of the subscriber and may not restart the transmission of the broadcast information to provide the subscriber with a smooth and seamless connection to the mobile network. Therefore, in the conventional setting, broadcast information is continuously transmitted otherwise the provision of a smooth and seamless connection environment is given up. If the broadcast information is not continuously transmitted, subscribers of the Home eNB or a family member of the subscriber must manually cut the connection before leaving the coverage area and must manually reconnect the Home eNB to the mobile network after returning home.
Further, when a Home eNB is installed in a school or a in a corporate setting, it is difficult to know when the last subscriber who has access to the Home eNB leaves the coverage area. For this reason, it is difficult for the subscriber to decide when to manually turn off the power.